Adding an @Immutable annotation to Java

Hi, I was thinking that it could be interesting adding an @Immutable annotation to Java. It would be a marker annotation for the compiler (similar to @FunctionalInterface) in order to throw an error if the annotated class/record has a component that is not @Immutable. This means that all existing immutable objects (like the primitive-wrapping objects and String) should be annotated with @Immutable and the programmer could, for example, annotate a new record object with @Immutable only if all its fields are annotated with @Immutable. What do you think? Regards, Alberto Otero Rodríguez.